I have a wonderful rat named Daisy. She's just about as sweet as can be. I take her out for hours of the day and she seems content, as she bruxes and boggles very often. I do feel guilty, though, as when I am away, she is left alone in her cage. I'm thinking of getting her a friend. The thing is, I've had Daisy for 8-9 months and she's gotten very used to being alone. I'm afraid that if I did end up buying another rat, she would be defensive/aggressive towards the other rat. What should I do?

First of all, try adopting or visiting a reputable breeder! A reputable rescue or breeder will help you find the perfect friend for Daisy and will help you with introductions. It's a very rare rat that is unsocial, especially after such a short time alone. All of my personal rats came from Craigslist, and had lived alone their entire lives, and they very quickly learned the joys of a big snuggly rat pile and having boxing matches with their siblings.

We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.

"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry

I would try a rescue or a reputable breeder first -- rats from Craigslist are very much like rats from pet stores -- they can be carrying any number of diseases, and you'll need to do a full 4 week quarantine before introductions. You can't quarantine in the same room, and it's even better not to quarantine in the same house!

We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.

"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry